Hydraulically operable road vehicle steering mechanisms



'June23,1959. w. H. BRIGGS 2,891,515

HYDRAUL ICALLY OPERABLEROAD VEHICLE STEERING MECHANISMS Filed Feb. e. 1956 5 Sheets-Sheet 1 nag/7171A June 23, 1959 w. H. BRIGG'S 2 9 1 HYDRAULICALLY OPERABLE ROAD VEHICLE STEERING MECHANISMS Filed mp6. 1956 :5 Sheets-Sheet 2 June 23,1959 w. H. BRIGGS I 2,391,515

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Ullltd StQIQS Zltfi HYDRAULICALLY OPERABLE ROAD VEHICLE STEERING MECHANISMS Walter Henry Briggs, Northfield, Birmingham, England, assignor to Burman & Sons Limited, Birmingham, England Application February 6, 1956, Serial No. 563,797

2 Claims. (Cl. 121-41) This invention has for its object to provide in a simple form a hydraulically operable road vehicle steering mechanism.

A steering mechanism in accordance with the invention comprises the combination of a working chamber, an oscillatory vane extending across the chamber and formed on or secured to a spindle for connection to the steerable road wheels, a screw-threaded spindle extending through the vane and operable by the driver, and a control valve comprising an outer part which occupies and is angnlarly movable within a cylindrical bore in the vane and a relatively movable inner part having a screw-thread connecion with the screw-threaded spindle, the various components of the apparatus being adapted to operate as herein described.

In the accompanying drawings Figure 1 is a sectional side elevation. Figure 2 a sectional end elevation and Figure 3 a plan of a mechanism embodying the invention. Figures 4, 5 and 6 are similar fragmentary sectional end views drawn to a larger scale than Figures 1 to 3, and showing the control valve in three different positions.

Referring to the drawings the working chamber a formed in a part of the housing b of the mechanism contains a transversely arranged oscillatory vane 0. At one end the vane is formed or secured a spindle d and to an outer end of the spindle is secured a drop arm e for connection to the steerable road wheels in a conventional manner.

The end of the vane adjacent to the spindle is shaped to a semi-circular form and is in close contact with a peripheral par-t of the working chamber of corresponding curvature. The other end of the vane is of segmental form having its center of curvature on the axis of the spindle, and this end is in close contact with a part of the periphery of the working chamber of corresponding curvature. Also the vane is gapped at each side as shown to permit its required range of movement relatively to the actuating spindle to be hereinafter described.

In the vane is for-med a transverse cylindrical bore having its axis parallel with the spindle d, and in the bore is contained a control valve.

The control valve comprises a hollow cylindrical member constructed from a pair of complementary parts 1, f which can oscillate within the said bore, and within this member is contained an internally screw-threaded collar g hereinafter referred to as the nut.

Inthe housing is also contained the actuating spindle h which is externally screw-threaded and passes through the valve and the gapped sides of the vane, and is embraced by the nut. At one end this spindle is supported by any conveniently constructed hearing i adapted to permit sufficient freedom of oscillation of the spindle when movement is imparted to the vane. Rotational movement of this spindle is efiected by another spindle (not shown) which is attached to the outer end of the spindle h and is operable by the driver.

The outer valve member is supported in the vane by trunnions j (Figure 2) and the parts 1, i of this member are shaped to form a cylindrical cavity for containing the nut. In one side of the part 1 of the valve are formed ports k communicating with the adjacent side of the working chamber, and in the part 7 are formed ports m in gomrnunication with the other adjacent part of the cham- The external diameter of the nut is made rather smaller than the diameter of the containing cavity so as to form an annular space through which the liquid can flow, and at diametrically opposite positions the nut has formed on it a pair of projections n which, when the nut is moved to either side of its neutral position can fit closely against the periphery of the containing cavity.

In the outer part of the valve are formed a pair of through a passage v in the ring s and an outlet passage w in the housing.

For securing the nut against inadvertent movement and also for limiting its angular movement relatively to the outer valve part, the latter part is provided with a plunger x loaded by a spring y and having a detent z which occupies a gap in one side of the nut.

The mode of action of the apparatus above described is as follows:

Assuming that the nut g occupies the position shown in Figures 2 and 4 relatively to the valve parts f, P, the motive liquid can flow freely from the inlet u to the outlet w by way of the annular space between the nut and the outer part of the valve. On the driver imparting a steering movement to the spindle h in the clockwise direction (looking at Figures 2 and 4) the first effect is to impart a corresponding angular movement to the nut, the amount of this movement of the nut being restricted by the detent z on the plunger x which is movable to a limited extent against the action of its loading spring 32. In such movement of the nut the upper projection 11 passes to a position beneath the passage p and the lower projection passes to a position above the passage 0 as shown in Figure 4, so isolating one half of the annular passage around the nut from the other half. The motive liquid then flows from the passage 0 through one half of the annular passage and thence through ports in into the right-hand side of the working chamber (Figure 1). Concurrently the liquid in the left-hand side of the chamber can pass out through the ports k and the other half of the annular passage to the passage p and thence to the outlet.

The etfect of the motive liquid in the right-hand side of the working chamber a is to move the vane c and spindle d in a clockwise direction for imparting the required steering movement to the road wheels. As this movement of the vane 0 must be accompanied by axial movement of the nut g, the latter is caused by the axial pressure exerted thereon to rotate on the actuating spindle in the direction for re-assuming its initial position relatively to the valve parts 1, f but so long as the driver continues to impart clockwise movement to the actuating spindle, the angular position of the nut relatively to the valve parts i, f remains unchanged, and the vane continues to move. Moreover, when the driver discontinues moving the actuating spindle h, the vane c continues to move to a small extent, and the axial movement imparted thereby to the nut g is accompanied by rotational movement of the nut into its initial neutral position relatively to the valve parts f, f whereupon the movement of the vane is discontinued, since the motive liquid can now flow idly through both halves of the annular passage between the nut and the valve part f.

When a counter-clockwise movement is given to the spindle h the nut is given a like movement and the motive liquid then passes through the valve to the left-hand side of the working chamber a, causing the vane to be moved in the opposite direction to that first described. In this condition the nut g occupies the position shown in Figure 6.

In the event of failure of the pump, the vane can be operated by the spindle it. Thus, when the initial angular movement of the nut g by the actuating spindle h is terminated by the detent 2, continued angular movement of the actuating spindle will, in the event of failure of the pump, cause angular movement of the vane, it being understood that the actuating spindle is incapable of axial movement, and when the initial angular movement of the nut by the actuating spindle is terminated with the pump out of action, continued angular movement of the actuating spindle must be accompanied by axial movement of the nut, and hence angular movement of the vane.

Having thus described my invention What I claim as new and desire to secure by Letters Patent is:

1. A hydraulically operable road vehicle steering mechanism comprising in combination a housing having therein a Working chamber, an oscillatory vane extending across the working chamber and having therein a cylindrical bore, a spindle rigid with and angularly movable by the vane, a screw-threaded spindle extending through the vane and operable by the driver, and a control valve having an outer part which occupies and is angularly movable within the cylindrical bore in the vane, and an inner part in screw-thread connection with the screw-threaded spindle, the inner part being movable relatively to the outer part by the screw-threaded spindle to control the flow of motive liquid to and from the working chamber csite sites of the vane.

2. A hydraulically operable road vehicle steering mechanism according to claim 1, and having means for limiting relative movement between the inner and outer parts of the control valve.

References Cited in the file o'f'this patent UNITED STATES PATENTS 1,467,208 Summer Sept. 4, 1923 1,937,485 Davis Nov. 28, 1933 1,947,991 Jessup Feb. 20, 1934 1,959,177 Sassen May 15, 1934 1,995,588 Secor Mar. 26, 1935 2,383,773 Chisholm Aug. 28, 1945 2,824,314 Davis Feb. 25, 1958 

